This invention relates to an apparatus for joining pieces of laminar material and in particular plywood core strips.
Machines have been proposed which join together wood strips intended for making up the core plies of plywood, or veneer strips in general, by applying thereon the jointing material such as adhesive tapes or threads in a perpendicular direction to the strip edges, and utilize a technique consisting in providing a succession of entraining conveyor floors, whereon the strips to be jointed edgewise are placed, and suitable pressure mechanisms capable of maintaining the strips in contact with such conveyor floors; these conveyor floors, which are composed each of a series of coplanar parallel conveyor belts arranged in spaced side-by-side relationship are characteristically driven at decreasing speeds, thereby the entrainment of the wood strips to be jointed towards the jointing material applying means is performed with a progressive slowing down of the foremost strips and consequent contacting therewith of the strips sequentially advanced from the feeding conveyor floor to the subsequent crowding conveyor floor coplanar therewith.
Known pressure mechanisms include pressing conveyor floors arranged above the entraining conveyor floors and adapted to press the wood strips against the underlying conveyor floors.
An example for this technique is described, for example, in U.S. Pat. Nos. 2,705,514 or 2,488,759.
The use of pressing conveyor floors of the above described type had among others the following drawbacks: p1 (a) The strips to be processed were clamped between the belts of the conveyor floors and entrained by both of them so that a sliding movement between the strips and the belts was difficult, thereby the crowding of the strips at the slower advancing conveyor floor was either impossible or caused excessive stresses both on the strips and the conveyor belts.
(b) The pressing conveyor floors require a complicated energy consuming driving and supporting mechanism, which occupied precious space above the entraining conveyor floors, thereby preventing adequate arrangement of devices for the transverse alignment of the strips and the devices for the application of the jointing material on the strips, in addition to the increased costs of the apparatus.